Introduction to radiomics for a clinical audience

Radiomics is a rapidly developing field of research focused on the extraction of quantitative features from medical images, thus converting these digital images into minable, high-dimensional data, which offer unique biological information that can enhance our understanding of disease processes and provide clinical decision support. To date, most radiomics research has been focused on oncological applications; however, it is increasingly being used in a raft of other diseases. This review gives an overview of radiomics for a clinical audience, including the radiomics pipeline and the common pitfalls associated with each stage. Key studies in oncology are presented with a focus on both those that use radiomics analysis alone and those that integrate its use with other multimodal data streams. Importantly, clinical applications outside oncology are also presented. Finally, we conclude by offering a vision for radiomics research in the future, including how it might impact our practice as radiologists.

Surgical outcomes for chronic exertional compartment syndrome following improved diagnostic criteria

INTRODUCTION

Chronic exertional compartment syndrome (CECS) presents with pain during exercise, most commonly within the anterior compartment of the lower limb. A diagnosis is classically made from a typical history and the measurement of intramuscular compartmental pressure (IMCP) testing. Improved, more specific diagnostic criteria for IMCP testing allow clinicians to now be more certain of a diagnosis of CECS. Outcomes following surgical treatment in patients diagnosed using these more robust criteria are unknown.

METHODS

All patients undergoing fasciectomy for anterior compartment CECS at a single rehabilitation unit were identified between 2014 and 2017. Wilcoxen signed-rank test was used to compare military fitness grading and paired t-test was used to compare Foot and Ankle Ability Measure, FAAM Sport Specific and Exercise-Induced LimbPain-G outcome measures, presurgery and postsurgery.

RESULTS

There was a significant difference in fitness grading between presurgical and postsurgical intervention (Z = -2.68, p < 0.01) with 46 % of patients improving their occupational medical grading. All secondary measures of outcome, looking at clinical symptoms, also improved.

CONCLUSION

Almost half of the patients undergoing fasciectomy, following diagnosis using more specific criteria, will have an improvement in occupational medical grading. These outcomes represent the lower end of those reported in civilian populations. This is likely a result of a combination of factors, most notably the different diagnostic criteria followed and the more stringent criteria applied to military occupational grading, compared with civilian practice. Further work is now required to evaluate the impact of differing rehabilitation regimes on postoperative patients identified through this more specific diagnostic testing.

Barefoot plantar pressure measurement in Chronic Exertional Compartment Syndrome

BACKGROUND

Patients with Chronic Exertional Compartment Syndrome (CECS) have exercise-limiting pain that subsides at rest. Diagnosis is confirmed by intramuscular compartment pressure (IMCP) measurement. Accompanying CECS, subjective changes to gait (foot slap) are frequently reported by patients. This has not previously been investigated. The aim of this study was to investigate differences in barefoot plantar pressure (BFPP) between CECS cases and asymptomatic controls prior to the onset of painful symptoms.

METHODS

40 male military volunteers, 20 with symptoms of CECS and 20 asymptomatic controls were studied. Alternative diagnoses were excluded with rigorous inclusion criteria, magnetic resonance imaging and dynamic IMCP measurement. BFPP was measured during walking and marching. Data were analysed for: Stance Time (ST); foot progression angle (FPA); centre of force; plantarflexion rate after heel strike (IFFC-time); the distribution of pressure under the heel; and, the ratio between inner and outer metatarsal loading. Correlation coefficients of each variable with speed and leg length were calculated followed by ANCOVA or t-test. Receiver operating characteristic (ROC) curves were constructed for IFFC-time.

RESULTS

Caseshad shorter ST and IFFC-times than controls. FPA was inversely related to walking speed (WS) in controls only. The area under the ROC curve for IFFC-time ranged from 0.746 (95%CI: 0.636-0.87) to 0.773 (95%CI: 0.671-0.875) representing 'fair predictive validity'.

CONCLUSION

Patients with CECS have an increased speed of ankle plantarflexion after heel strike that precedes the onset of painful symptoms likely resulting from a mechanical disadvantage of Tibialis Anterior. These findings provide further insight into the pathophysiology of CECS and support further investigation of this non-invasive diagnostic. The predictive value of IFFC-time in the diagnosis of CECS is comparable to post-exercise IMCP but falls short of dynamic IMCP measured during painful symptoms.

Effects of anterior compartment fasciotomy on intramuscular compartment pressure in patients with chronic exertional compartment syndrome

Background

Patients with chronic exertional compartment syndrome (CECS) have pain during exercise that usually subsides at rest. Diagnosis is usually confirmed by measurement of intramuscular compartment pressure (IMCP) following exclusion of other possible causes. Management usually requires fasciotomy but reported outcomes vary widely. There is little evidence of the effectiveness of fasciotomy on IMCP. Testing is rarely repeated postoperatively and reported follow-up is poor. Improved diagnostic criteria based on preselection and IMCP levels during dynamic exercise testing have recently been reported.

Objectives

(1) To compare IMCP in three groups, one with classical symptoms and no treatment and the other with symptoms of CECS who have been treated with fasciotomy and an asymptomatic control group. (2) Establish if differences in IMCP in these groups as a result of fasciotomy relate to functional and symptomatic improvement.

Methods

Twenty subjects with symptoms of CECS of the anterior compartment, 20 asymptomatic controls and 20 patients who had undergone fasciotomy for CECS were compared. All other possible diagnoses were excluded using rigorous inclusion criteria and MRI. Dynamic IMCP was measured using an electronic catheter wire before, during and after participants exercised on a treadmill during a standardised 15 min exercise challenge. Statistical analysis included t-tests and analysis of variance.

Results

Fasciotomy results in reduced IMCP at all time points during a standardised exercise protocol compared with preoperative cases. In subjects responding to fasciotomy, there is a significant reduction in IMCP below that of preoperative groups (P<0.001). Postoperative responders to fasciotomy have no significant differences in IMCP from asymptomatic controls (P=0.182).

Conclusion

Fasciotomy reduces IMCP in all patients. Larger studies are required to confirm that the reduction in IMCP accounts for differences in functional outcomes and pain reductions seen in postoperative patients with CECS.

Isolated Lateral Meniscal Tear in the Dog

degenerative changes of the involved stifle joint associated with a “bucket handle” tear of the caudal body of the lateral meniscus. Surgical excision of the torn section of meniscus was beneficial in the first patient but this patient had persistant difficulty with the leg after exercise. Gross and microscopic pathology of the involved stifle in the second patient showed the meniscal lesion to be associated with severe cartilage fibrillation of the overlying lateral femoral condyle. As in human beings, the mechanism of injury may have been placement of the foot during vigorous external rotation of the femur with the stifle flexed. Extension of the limb from this position could have resulted in an isolated tear of the lateral meniscus.

Effect of intramedullary pin size on reducing bone plate strain

The degrees of plate strain, coupled with various diameters of intramedullary pins, is reported. In addition, the fatigue life and stiffness of the plate/pin construct was determined.

Extra-articular stabilization of the cranial cruciate deficient stifle with anchor systems

Complete or partial rupture of the cranial cruciate ligament (CCL) is a common injury of the canine stifle. Most practicing veterinarians would agree that optimal outcome is best achieved with surgical intervention. A popular method of stabilization is an extra-articular suture stabilization. The objective of this manuscript is to describe suture placement in a more isometric position as compared to traditional suture placement. A second objective is to introduce the veterinary surgeon to novel anchor products used for stabilization.

Cranial cruciate ligament rupture in large and giant dogs

Forty-two dogs weighing between 30 and 87 kg (mean body weight of 49 kg) with cranial cruciate ligament ruptures (CCLR) were treated with a modified lateral extra-capsular stabilization using braided polyester prosthetic ligament-suture anchor technique. Clinical and radiographic outcomes of 48 stifles were retrospectively evaluated with a mean follow-up of 18 months. Ten dogs had pulled out their bone anchors with no clinical relevance. Draining tracts did not appear. Despite mild radiographic progression of osteoarthritis, all of the dogs regained acceptable function of the operated limb.

Extra-articular stabilization of the cranial cruciate deficient stifle with anchor systems

Complete or partial rupture of the cranial cruciate ligament (CCL) is a common injury of the canine stifle. Most practicing veterinarians would agree that optimal outcome is best achieved with surgical intervention. A popular method of stabilization is an extra-articular suture stabilization. The objective of this manuscript is to describe suture placement in a more isometric position as compared to traditional suture placement. A second objective is to introduce the veterinary surgeon to novel anchor products used for stabilization.

Comparison of dynamic ultrasound and stress radiology for assessment of inferior glenohumeral laxity in asymptomatic shoulders

OBJECTIVE

To determine the level of agreement between dynamic ultrasound imaging and stress radiography used for the measurement of inferior glenohumeral laxity in asymptomatic shoulders, and to determine the repeatability of the dynamic ultrasound technique.

MATERIALS AND METHODS

Using a custom-made stress device to apply an inferior displacement force of 90 N, we assessed 20 asymptomatic male subjects for inferior glenohumeral laxity, using stress radiography and dynamic ultrasound. Paired differences between the two methods were evaluated by the 95% limits of agreement method. At a separate session, 19 subjects had inferior glenohumeral laxity assessed by two observers, using dynamic ultrasound. Inter- and intra-observer repeatability was determined for the ultrasound technique.

RESULTS

The mean [(+/-standard deviation (SD)] inferior translation was 4.7+/-4.1 mm by stress radiography and 4.4+/-2.3 mm by dynamic ultrasound. The 95% limits of agreement showed good agreement between the two methods. The paired difference between the two measurement methods varied with the magnitude of the measurement (P<0.001). Intra-observer repeatability of dynamic ultrasound was determined by the use of intra-class correlation coefficients and was 0.94 and 0.89 for the two investigators. Inter-observer repeatability was 0.85. The standard error of the measurement was 0.60 mm and 0.66 mm, for repeated measurements by the two investigators, and 0.85 mm between investigators. Repeatability coefficients demonstrated excellent consistency of measurement between sessions and good consistency between observers.

CONCLUSION

Dynamic ultrasound is a valid and reproducible method for the assessment and quantification of inferior glenohumeral laxity.

Cranial cruciate ligament rupture in large and giant dogs. A retrospective evaluation of a modified lateral extracapsular stabilization

Forty-two dogs weighing between 30 and 87 kg (mean body weight of 49 kg) with cranial cruciate ligament ruptures (CCLR) were treated with a modified lateral extra-capsular stabilization using braided polyester prosthetic ligament-suture anchor technique. Clinical and radiographic outcomes of 48 stifles were retrospectively evaluated with a mean follow-up of 18 months. Ten dogs had pulled out their bone anchors with no clinical relevance. Draining tracts did not appear. Despite mild radiographic progression of osteoarthritis, all of the dogs regained acceptable function of the operated limb.

Treatment methods for pain in the osteoarthritic patient

Osteoarthritis is one of the most common clinical problems for which pet owners seek veterinary consultation. Proper management of osteoarthritis is rewarding to the patient, client, and veterinarian alike. The foundation for treatment of osteoarthritis is weight control, exercise moderation, and administration of anti-inflammatory agents. This section of the text addresses clinically important mechanisms of osteoarthritis and the use of anti-inflammatory agents targeted to reduce pain and inflammation associated with the disease.

Reduction in plate strain by addition of an intramedullary pin

OBJECTIVE

The purpose of this study was to determine the strain sparing effect of a bone plate and rod system compared with a bone plate alone.

STUDY DESIGN

Mathematical analysis and in vitro modeling of implant-bone constructs. Implants were instrumented with uniaxial strain gauges. ANIMALS OR SAMPLE PREPARATION: Five pairs of canine femurs.

METHODS

Bone plates were instrumented with two 350-ohm strain gauges. The bone plates were used to bridge a simulated fracture gap in five pairs of canine femurs. In one femur of each pair, a bone plate alone was used to bridge the gap; in the opposite femur, a bone plate and intramedullary rod combination was used. Each specimen was mounted on a custom jig and loaded in an axial servohydraulic testing machine. A constantly increasing compressive load was applied at the rate of 0.7 cm/sec. Strains at 400.5 N were recorded and analyzed using Wilcoxon's signed rank test. Mathematical modeling was done using parallel beam theory.

RESULTS

Stress reduction in the plate and rod system was twofold compared with the plate alone (P = .059). As important, based on stress reduction in the plate, the fatigue life of the plate/rod system increased 10-fold over the plate system alone and was greater than 10-fold at higher absolute stress values. Mathematical analysis of the plate/rod system was similar to that seen with the in vitro analysis.

CONCLUSIONS

The combination of a bone plate and intramedullary pin was superior in reducing plate stress when compared with the plate alone and functioned as two beams acting in concert.

CLINICAL RELEVANCE

Stabilization of comminuted fractures by bridging the zone of fragmentation with a bone plate without anatomic reduction of each fragment is a useful method of managing this type of injury. Addition of an intramedullary pin reduces the stress applied to the plate and thereby extends the fatigue life of the bone plate.

Effects of anaesthetics on membrane mobility and locomotor responses of human neutrophils

The morphological response of neutrophils to chemotactic factors is characterized by an immediate change (in seconds) from a spherical to an irregular shape. Within two or three minutes, the cells assume the head-tail polarity typical of locomotor cells. In this study the effects of the anaesthetic drugs, propofol and thiopentone, on the time-sequence of the morphological response of human neutrophils to the chemotactic peptide fMet-Leu-Phe were examined. At concentrations seen in the plasma during anaesthesia, both drugs inhibited both the rate and degree of the neutrophil chemotactic response. The effect of propofol was not attributable to its lipid vehicle, as 10% intralipid alone had no effect on neutrophil polarization. Plasma membrane reorganization occurs during polarization of neutrophils, resulting in morphological and functional changes which prepare the cells for chemotaxis and phagocytosis. Fluorescence recovery after photobleaching (FRAP) was used to investigate effects of the anaesthetics on membrane lipid behaviour. With a lipid probe, the proportion of mobile lipid in neutrophils exposed to propofol or thiopentone was reduced. There was a less significant reduction with intralipid which also caused reduction in velocity of lateral diffusion of the probe. These findings suggest that the inhibitory effects of anaesthetics on neutrophil locomotion are related to reductions in fluid mobility of the plasma membranes of anaesthetic-treated cells.

Autoantibody associations with MHC class II antigens in scleroderma and autoimmune vasculitis

HLA-DR haplotypes in patients with scleroderma and vasculitis were compared with those in healthy controls from the Scottish population to investigate whether any associations exist between MHC antigens and development of specific autoantibodies. In patients with systemic vasculitis the presence of any antibodies against neutrophil cytoplasmic antigens (ANCA) was associated with an increased frequency of DR8 [p < 0.004], and no patients expressed the DR5 antigen. However, no significant differences were observed when these patients were subdivided into those with anti-myeloperoxidase (MPO) antibodies or anti-proteinase-3 (PR3) antibodies. Scleroderma patients as a whole showed a lower frequency of DR7 than controls [5.1% cf 28% in control population, p < 0.002]. Following subdivision by autoantibody profile, patients with circulating anti-centromere antibody (ACA) showed an increased frequency of DR1 compared to the control population [p < 0.001]. No scleroderma patient without ACA expressed this haplotype. Associations between MHC and some autoantibodies suggest that antigen presentation could lead to their production.

Biomechanics of fracture fixation failure

This article reviews the physiologic forces, stresses, and strains in normal bones. Biomaterials used in implants for fracture fixation devices are described, and the mechanical properties of an implant are discussed. The common mechanisms of implant failure are included.

Effect of beta-tricalcium phosphate in surgically created subchondral bone defects in male horses

beta-Tricalcium phosphate (TCP) was evaluated as a synthetic bone grafting material in horses. Sixteen horses were randomly assigned to 4 groups of 4 horses. In each horse, an 11-mm by 10-mm circular defect with a smooth margin was created surgically in the weight-bearing surface of both third metacarpal bones (McIII) and the left third metatarsal bone. The defect in the left McIII was filled with TCP, the defect in the right McIII was filled with a mixture of 50% autogenous cancellous bone (ACB) and 50% TCP, and the defect in the left third metatarsal bone was not filled to serve as a control. Nuclear imaging and radiographic evaluation of surgical sites were performed at postsurgical week (PSW) 4 and 13 in group-I horses and at PSW 26, 39, and 52 in groups-II, -III, and -IV horses, respectively. Horses in groups I, II, III, and IV were euthanatized at PSW 13, 26, 39, and 52, respectively, and specimens were harvested for histologic evaluation. Results were compared among treatment methods, as well as among time intervals. The greatest activity at defect sites was seen in group-I horses at PSW 4. Activity counts in limbs of group-I horses at PSW 13 and counts in limbs of group-II horses at PSW 26 were not significantly (P less than or equal to 0.05) different. Activity counts in groups-III and -IV horses at PSW 39 and 52, respectively, were less than those in groups I and II. However, there was no significant difference in activity counts between limbs implanted with TCP or ACB:TCP.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of postoperative electromagnetic pulsing on canine posterior spinal fusions

An experimental canine study was devised to evaluate the efficacy of a noninvasive adjunct to improve the rate and quality of the posterior fusion mass over the standard surgical technique. Ten large adult mongrel dogs underwent a three-level lumbar spinal fusion. Bone excised from the spinous processes was packed in removed facet joints and over the decorticated laminae. To insure rigid internal fixation, custom-made distraction instrumentation was placed bilaterally under the laminae of the vertebrae above and below the three fused vertebrae. Five dogs underwent electromagnetic pulsing, and five dogs acted as controls. Two dogs were sacrificed at 4, 6, 9, 12, and 15 weeks to assess the radiographic and histologic status of the fusion mass. Preoperative and preautopsy hematologic studies as well as gross and histologic autopsy specimens revealed no abnormalities attributable to the electromagnetic pulsing. High-resolution radiography and histologic studies showed earlier incorporation of the graft, improved new bone formation, and better organization of the fusion mass in the 4-, 6-, and 9-week stimulated specimens. However, by 12 and 15 weeks there did not appear to be any histologic or radiographic differences between the stimulated and control dogs. Although electromagnetic pulsing appears to produce an early accelerated osteogenic response, it does not appear to improve the overall results of primary canine spinal fusions.